Circuit breaker



CIRCUIT BREAKER Filed July 22, 1950 WITNESSES: I INVENTORS Ric o d H. He an on vel G. 'un.

Patented Dec. 30, 1952 CIRCUIT BREAKER Richard H. Herman, Lima, and Orvel G. Killian, Wapakoneta, Ohio, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 22, 1950, Serial No. 175,314

6 Claims. 1

This invention relates to circuit breakers and more particularly to circuit breakers for controlling lighting circuits and small to moderate power low voltage circuits.

An object of the invention is to provide an improved circuit breaker of the class described that is simple and compact, accurate and reliable in operation and economical to manufacture.

Another object of the invention is to provide a circuit breaker embodying an improved snapaction operating mechanism that is manually operable to open and close the breaker and that is adapted to be tripped by a current responsive trip element in response to predetermined overload conditions to cause automatic opening of the breaker.

Another object of the invention is to provide a circuit breaker embodying an improved operating mechanism that is trip-free of the operating handle.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a vertical sectional view of a circuit breaker embodying the principles of the invention,the circuit breaker being shown in the closed position.

Fig. 2 is a view similar to Fig. l but showing the circuit breaker in the manually opened position.

Fig. 3 is a view similar to Figs. 1 and 2 but showing the breaker in the tripped open position.

Fig. 4 is a vertical sectional view taken on line IV- IV of Fig. 1 and looking in the direction indicated by the arrows.

Referring to Figs. 1 to 3 of the drawing, the circuit breaker includes a base ll of insulating material upon which is mounted a pair of terminal members 13 and I5, a U-shaped frame 11 and a current responsive trip device 19.

The terminal l3 extends inside the base H and has an angular portion 2| thereof secured by means of a screw 23 to the adjacent end Wall of the base. One foot 25 (Fig. 1) of a U-shaped bimeta1 element 21 is rigidly secured to the terminal l3 and the other foot 29 (Fig. 2) of the bimetal element is rigidly secured to an angular support member 3| (Fig. 2) which is secured to the adjacent end wall of the base II by means of a screw 33. A stationary contact 35 is rigidly mounted on an angular support 31 which is rigidly mounted on the support member 3 I.

The terminal l5 also extends inside the base i l and is secured by means of a screw 39 to the adjacent end wall of the base. A plate 41 of conductin material is secured to the terminal I5 inside the base and is electrically connected by means of a flexible connection 43 to a movable U-shaped switch member or arm 45 which carries a movable contact 41 for cooperating with the stationary contact 35. The legs 48 of the U-shaped switch arm 45 are pivotally connected by means of pivot pins 49 to the spaced legs 50 of the bifurcated free end of a releasable member 5! pivotally mounted on a pivot pin 53 supported in the frame ll. Also pivotally mounted on the pin 53 is an operating lever 55 of molded insulating material having its inner end bifurcated and the two legs 51 thereof disposed one on each side of the releasable member 5| as clearly shown in Fig. 4. A handle 59 integral with the operating lever extends through an opening in a cover plate 5i and an arcuate portion 63 of the operating lever is disposed to substantially close the handle opening in all positions of the handle.

The ends of the legs 57 of the operating lever 55 are provided with slots 65 which cooperate with a rod 61 carried by the upper ends of a pair of levers 63. The levers 69 are disposed one on each side of the operating lever as shown in Fig. 4 and are individually pivoted on fixed pivot pins ll mounted in the frame members [1. An overcenter spring 13 is connected under tension between the rod 61 and the bight of the U-shaped switch arm 45. The releasable member 5! is biased in a counterclockwise direction about the pivot 53 by means of a trippin spring '15 having one end hooked over a pin 11 in the member 51 and the other end hooked over a pin 19 supported between the side members of the frame 11. The pin 19 also serves as a stop to limit the movement of the releasable member during an automatic opening operation. The releasable member 5! is normally restrained against counterclockwise movement by a latching projection 81 thereon engaging a latch element 83 secured to the bimetal element 21 adjacent its free end.

In order to reduce the heat radiation losses and to obtain maximum temperature rise in the bimetal element 21 on overloads of lower magnitude, a shield 84 of mica or other suitable insulating material is provided. The shield 84 is rigidly secured to the free end of the bimetal element 21 between the bimetal and the latch element 83 and extends inwardly along the bimetal element.

The circuit breaker is manually operated to open and close the contacts by movement of the handle 59 to the oil and on positions. To open the contacts 354'l, the handle 59 is rotated clockwise from the on position (Fig. l) to the oil position (Fig. 2) During this movement the legs 57 of the operating lever 55 carries the rod 61, and hence, the upper end of the overcenter spring 13 across to the left of a line drawn through the pivot pin 49 and the point ofattachment ofv the spring 13 to the bight of the switch arm 45. The spring 13 then biases the switch arm 45 in opening direction and quickly moves it to the open position (Fig. 2) with a snap action, the switch arm being arrested in the open position by engaging a stop member 35 rigidly mounted on the side members of the, frame ii.

In order to close the breaker contacts the handle 59 is rotated counterclockwise from the off position (Fig. 2) to the on position (Fig. 1). During this movement the operating lever 55 carries the overcenter spring i3 across to the right or" the center line of the switch arm 55 whereupon the spring '53 biases the switch arm in closing direction and closes the contacts with a snap action.

Upon the occurrence of an overload current the bimetal element 27 becomes heated in response to the flow of excessive current therethrough and, when heated a predetermined amount, the free end thereof deflects toward the right causing the latch element 83 to release the releasable member 5! whereupon the tripping spring 15 rotates the releasable member counterclockwise about the pivot 53 until itis arrested by the stop pin 19. During the counterclockwise movement of the releasable member the pivot 49, by which the switch arm 25 is pivotally connected to the free end of the releasable member, is moved across to the right of the line of action of the overcenter spring l3. As soon as the pivot dlicrosses to the right of the line of action of the spring 13, the spring biases the switch arm &5 in opening direction and rotates the switch arm clockwise to open the contacts with a snap action. As shown in Fig. 3, the switch arm M) is inthe open position against the stop 35 in which position the line of action oi the spring 13 is to the left of the fixed pivots H for the levers '69. Consequently, the spring '53 biases these leversin a counterclockwise direction and, through the rod 6?, biases the operating lever clockwise until it is stopped by a resetting surfaces-l on the arcuate portion 63 thereof strikingthe releasable member 5! as shown in Fig. 3. In this position of the operating lever 55 the operating handle 59 occupiesa central position wherein it serves as a visual indication of the tripped open condition of the breaker.

Before the contacts can be closed following an automatic tripping operation, the releasable member must be reset and the latching por-tion8l thereof reengaged with the latch element 83 on the bimetal element. This is eiiected by rotating the handle 59 from the central indicating position (Fig. 3) clockwise to the full off position (Fig. 2). During this movement the resetting surface 81 on the operating lever moves the releasable member 5! clockwise therewith, the latching projection Bl slightly deflecting the bimetal element against its normal bias until the projectionfll clears the latching surface on the,

latch element 83. The bimetal element then springs back to latching position, as shown in Fig. 2, to again releasably restrain the releasable member 5!. The contacts may now be closed by movement of the handle 59 to the on position in the previously described manner.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details, arrangement of parts and combination of elements may be made without departing from some of the essential features of the invention.

We claimas our invention:

1. A circuit breaker having relatively movable contacts, operating mechanism including an operat ng member movable to effect opening and closing of said contacts, a releasable member operable when released to effect automatic opening of said contacts, a switch member pivotally connected to the free end of said releasable member, a lever pivoted on a fixed pivot and, having connecting means engaging said operating member to be operated thereby, an overcenter spring connected under tension to the free end of said switch member and to said connecting means operable by said operating member to manually open and close said contacts while said releasable member remains stationary, said overcenter spring in the closed position of said operating mechanism being incapable of moving said re,-. leasable member in opening direction upon release of said releasable member, trip means for effecting release of said releasable member, and separate spring means for operating said releasable member when said member is released by said trip means to effect automatic opening of said contacts.

2. A circuit breaker comprising stationary and, movable contacts, operating mechanism for said contacts including an operating member movable to effect opening and closing of said contacts, a

releasable member operable when releasedto effect automatic opening of said contacts, means providing a fixed pivot supporting said operating member and said releasable member for movement about a common axis, a switch memberhaving one end pivotally connected to the free end of,

said releasable member, a lever pivoted on a fixed pivot and having connecting means engaging. said operating member to be operated thereby, an.

overcenter spring tensioned between the other end of said switch member and said connecting;

means operable by said operating member. to manually open and close said contacts, said overcenter spring in the closed position of said op-.. erating mechanism being incapable of moving said releasable member in opening direction upon,

release thereof, trip means for effecting release of said releasable member, and separate spring means for operating said releasable member when said member is released by said trip means to effect automatic opening of said contact means.

3. Acircuit breaker having relatively movable contacts, operating mechanism including an, op,-v erating member movable to effect opening and closing of said contacts, a releasable member pivotally mounted at one end and operable when,re-- leased to efifect automatic opening. of said con.

tacts, a switch arm having one end pivotally, C011:-

nected to the other end of said releasablemember,

an overcenter spring having one end connected to the free end or" said switch arm and the other; end operable by said operating member for op-. erating said switch arm to open and, close,- said, contacts, said overcenter spring in the closed position of said mechanism being incapable of actuating said releasable member upon release thereof, trip means releasably engaging said releasable member at a point intermediate the ends thereof to releasably restrain said releasable member in operative position, said trip means being operable in response to overload currents to release said releasable member, and separate spring means at all times biasing said releasable member in opening direction and operable upon release of said releasable member to move said member in a direction to cause opening of said contacts.

4. A circuit breaker having relatively movable contacts, operating mechanism including a pivoted operating member movable to effect manual opening and closing of said contacts, fixed pivot means pivotally supporting said operating member, a releasable member having one end pivotally mounted on said fixed pivot means and operable when released to effect automatic opening of said contacts, a switch member having one end pivotally connected to the other end of said releasable member, an overcenter spring having one end connected to the free end of said switch member operable by said operating member to manually open and close said contacts while said releasable member remains stationary, trip means engaging said releasable member at a point intermediate the ends of said releasable member for normally restraining said releasable member in operative position, and said trip means being operable in response to overload currents to release said releasable member and effect automatic opening of said contacts.

5. A circuit breaker having relatively movable contacts, operating mechanism including an operating member movable to effect opening and closing of said contacts, a releasable member pivotally mounted at one end having a latching surface intermediate the ends therof and operable when released to effect automatic opening of said contacts, a switch arm having one end pivotally connected to the other end of said releasable member, spring means having one end connected to the free end of said switch arm and the other end operable by said operating member to effect opening and closing of said contacts, said spring means in the closed position of said operating mechanism being incapable of moving said releasable member in opening direction upon release of said releasable member, trip means normally engaging said latching surface to releasably restrain said releasable member in operative position, said trip means being operable in response to overload currents to unlatch said releasable member, and separate spring means at all times biasing said releasable member in opening direction and operable upon release of said releasable member to move said member in opening direction to efiect automatic opening of said contacts.

6. A circuit breaker having relatively movable contacts, operating mechanism including an operating member movable to effect opening and closing of said contacts, a releasable member pivotally mounted at one end having a latching surface intermediate the ends thereof and operable when released to effect automatic opening of said contacts, a switch arm having one end pivotally connected to the other end of said releasable member, an overcenter spring having one end connected to the free end of said switch arm and the other end operable by said operating member to effect opening and closing of said contacts, said overcenter spring in the closed position of said contacts being incapable of actuating said releasable member, trip means normally engaging said latching surface to releasably restrain said releasable member in operative position, and said trip means being operable in response to overload currents to unlatch said releasable member and effect automatic opening of said contacts and additional spring means at all times biasing said releasable member in opening direction and operative upon release of said releasable member to actuate said releasable member.

RICHARD H. HERMAN. ORVEL G. KILLIAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,467,797 Wise Apr. 19, 1949 2,494,868 Geremia Jan. 17, 1950 

